1. Field of the Invention
This invention relates to processes and compositions for rendering inorganic substrate materials hydrophobic. This invention also relates to the processing of low cost bulk earthen materials and inorganic industrial waste materials into value added, marketable and useable products.
2. Description of the Prior Art
Hydrophobic silicas are known to be water repellant. This physical feature makes these materials unique in their application, since water is ubiquitous in the environment, and most materials, primarily inorganic materials, are readily wetted by water. Hydrophobic materials can be used in a variety of commercial applications which require this unique physical characteristic. Examples of such materials include AROSIL R-202 by Degussa Chemical Corporation (Richfield Park, N.J.) and CAB-O-SIL TS-530 by Cabot Chemical Corporation (Tuscola, Ill.). Examples are also described in Cottrell (U.S. Pat. No. 3,963,627) and Laufer (U.S. Pat. No. 3,948,676). Unfortunately, however, the relative cost of these hydrophobic silicas make them prohibitive for widespread use and in bulk applications.
The application of siloxanes to earthen and small particle size materials has been described (Price, U.S. Pat. No. 4,478,911). The use of mechanical coatings of hydrophobic silicas over large porous substrates has also been described (Tully, U.S. Pat. No. 4,102,703).
It would be desirable to render small particle size (less than 1 cm in diameter) bulk inorganic materials such as sand, pulverized slag, minerals, incinerator ash, and other industrial waste materials hydrophobic prior to application or fabrication. It would further be desirable to provide materials with longer lasting and more effective hydrophobic properties, which are more resistent to weathering than the products presently available for this application.